<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
  <div id="app-1">
    <p>{{ msg }}</p>
  </div>
  <div id="app-2">
    <p>{{ msg }}</p>
  </div>
  <script>
    const vue1 = new Vue({
      el: '#app-1',
      data: {
        msg: 'app-1'
      }
    })
    const vue2 = new Vue({
      el: '#app-2',
      data: {
        msg: 'app-2'
      }
    })
  </script>
</body>
</html>